Your humidifier is equipped with a built-in humidity sensor. This sensor is connected to a humidity indicator light: the color of this humidity indicator light shows whether the set target is reached or not.
How do the red and blue indicator lights in my Philips Humidifier work?
Humidity indicator light: blue or red
When the desired humidity level is reached, the color of the humidity indicator light is blue. When the humidity level is not reached, the color of the humidity indicator light becomes red.
Low water indicator light: red
There is a float (a floating ball) inside your Philips Humidifier’s tank. When the water level becomes low, the float activates a water level switch and this will activate the red indication.
Note: sometimes, this floating ball can be stuck and fail to activate the water level switch. When this happens, your humidifier will not display a low water indicator. You can solve this by moving this ball with your hand.